如何使 for 循环等待所有异步函数完成。 异步函数里面有多个异步函数

Question

I have an array, like [1,2,3,4,5,6,7,8,10].

I like to process one item at a time. synchronously.

I have mixed with non-async functions too.

var array = [1,2,3,4,5,6,7,8,9,10]
for(i=0; i< array.length; i++){
    var result = await fun1(array[i]);
    console(result) //expecting print out 2,4,6,8,10...20 synchronously
}

async function fun1(item){
    return fun2(item);
}
async function fun2(item){
    a = new A(item)
    return a.hello()
}

class A{
    constructor(item){
       this.item = item;
    }

    hello(){
        //do something
        return this.item * 2;
    }
}

How can I make it happen in Node.JS?

Answer 1

you can use Promise.all feature.

const promises = [];
const array = [1,2,3,4,5,6,7,8,9,10]
array.forEach((num)=>{
  promises.push(func1(num))
});

Promise.all(promises)
.then(response => console.log(response)); // your required response